diff --git a/hypervisor/arch/x86/guest/instr_emul.c b/hypervisor/arch/x86/guest/instr_emul.c
index 072ae80e8..2a73ae08f 100644
--- a/hypervisor/arch/x86/guest/instr_emul.c
+++ b/hypervisor/arch/x86/guest/instr_emul.c
@@ -2338,7 +2338,7 @@ int decode_instruction(struct vcpu *vcpu)
 		instr_check_gva(vcpu, emul_ctxt, cpu_mode);
 	}
 
-	return  emul_ctxt->vie.opsize;
+	return (int)(emul_ctxt->vie.opsize);
 }
 
 int emulate_instruction(struct vcpu *vcpu)
diff --git a/hypervisor/arch/x86/guest/vlapic.c b/hypervisor/arch/x86/guest/vlapic.c
index 9da2fcc8e..c934bc15e 100644
--- a/hypervisor/arch/x86/guest/vlapic.c
+++ b/hypervisor/arch/x86/guest/vlapic.c
@@ -289,7 +289,7 @@ static void vlapic_reset_timer(struct acrn_vlapic *vlapic)
 
 	timer = &vlapic->vtimer.timer;
 	del_timer(timer);
-	timer->mode = 0;
+	timer->mode = TICK_MODE_ONESHOT;
 	timer->fire_tsc = 0UL;
 	timer->period_in_cycle = 0UL;
 }
diff --git a/hypervisor/arch/x86/ioapic.c b/hypervisor/arch/x86/ioapic.c
index 9cd1caf7a..cde81b7bd 100644
--- a/hypervisor/arch/x86/ioapic.c
+++ b/hypervisor/arch/x86/ioapic.c
@@ -98,9 +98,9 @@ ioapic_read_reg32(const void *ioapic_base, const uint32_t offset)
 	spinlock_irqsave_obtain(&ioapic_lock, &rflags);
 
 	/* Write IOREGSEL */
-	mmio_write32(offset, (void *)ioapic_base + IOAPIC_REGSEL);
+	mmio_write32(offset, ioapic_base + IOAPIC_REGSEL);
 	/* Read  IOWIN */
-	v = mmio_read32((void *)ioapic_base + IOAPIC_WINDOW);
+	v = mmio_read32(ioapic_base + IOAPIC_WINDOW);
 
 	spinlock_irqrestore_release(&ioapic_lock, rflags);
 	return v;
@@ -115,9 +115,9 @@ ioapic_write_reg32(const void *ioapic_base,
 	spinlock_irqsave_obtain(&ioapic_lock, &rflags);
 
 	/* Write IOREGSEL */
-	mmio_write32(offset, (void *)ioapic_base + IOAPIC_REGSEL);
+	mmio_write32(offset, ioapic_base + IOAPIC_REGSEL);
 	/* Write IOWIN */
-	mmio_write32(value, (void *)ioapic_base + IOAPIC_WINDOW);
+	mmio_write32(value, ioapic_base + IOAPIC_WINDOW);
 
 	spinlock_irqrestore_release(&ioapic_lock, rflags);
 }
diff --git a/hypervisor/include/arch/x86/guest/guest.h b/hypervisor/include/arch/x86/guest/guest.h
index 314efdfa5..9ea1430c0 100644
--- a/hypervisor/include/arch/x86/guest/guest.h
+++ b/hypervisor/include/arch/x86/guest/guest.h
@@ -132,7 +132,6 @@ int rdmsr_vmexit_handler(struct vcpu *vcpu);
 int wrmsr_vmexit_handler(struct vcpu *vcpu);
 void init_msr_emulation(struct vcpu *vcpu);
 
-extern const char vm_exit;
 struct run_context;
 int vmx_vmrun(struct run_context *context, int ops, int ibrs);
 
diff --git a/hypervisor/include/arch/x86/timer.h b/hypervisor/include/arch/x86/timer.h
index 9e3733a8b..e2688c793 100644
--- a/hypervisor/include/arch/x86/timer.h
+++ b/hypervisor/include/arch/x86/timer.h
@@ -20,7 +20,7 @@ struct per_cpu_timers {
 
 struct hv_timer {
 	struct list_head node;		/* link all timers */
-	int mode;			/* timer mode: one-shot or periodic */
+	enum tick_mode mode;			/* timer mode: one-shot or periodic */
 	uint64_t fire_tsc;		/* tsc deadline to interrupt */
 	uint64_t period_in_cycle;	/* period of the periodic timer in unit of TSC cycles */
 	timer_handle_t func;		/* callback if time reached */
diff --git a/hypervisor/include/arch/x86/vmexit.h b/hypervisor/include/arch/x86/vmexit.h
index 3ae3873a4..48baf7a8a 100644
--- a/hypervisor/include/arch/x86/vmexit.h
+++ b/hypervisor/include/arch/x86/vmexit.h
@@ -16,7 +16,7 @@ int vmexit_handler(struct vcpu *vcpu);
 int vmcall_vmexit_handler(struct vcpu *vcpu);
 int cpuid_vmexit_handler(struct vcpu *vcpu);
 int cr_access_vmexit_handler(struct vcpu *vcpu);
-
+extern void vm_exit(void);
 static inline uint64_t
 vm_exit_qualification_bit_mask(uint64_t exit_qual, uint32_t msb, uint32_t lsb)
 {
diff --git a/hypervisor/include/debug/npk_log.h b/hypervisor/include/debug/npk_log.h
index 80e693795..09e2cab05 100644
--- a/hypervisor/include/debug/npk_log.h
+++ b/hypervisor/include/debug/npk_log.h
@@ -20,13 +20,12 @@ enum {
 	HV_NPK_LOG_CMD_QUERY,
 };
 
-enum {
-	HV_NPK_LOG_RES_INVALID,
-	HV_NPK_LOG_RES_OK,
-	HV_NPK_LOG_RES_KO,
-	HV_NPK_LOG_RES_ENABLED,
-	HV_NPK_LOG_RES_DISABLED,
-};
+
+#define	HV_NPK_LOG_RES_INVALID	0x1U
+#define	HV_NPK_LOG_RES_OK	0x2U
+#define	HV_NPK_LOG_RES_KO	0x3U
+#define	HV_NPK_LOG_RES_ENABLED	0x4U
+#define	HV_NPK_LOG_RES_DISABLED	0x5U
 
 struct hv_npk_log_param;